| Verify RHEL 8 ignores IPv4 ICMP redirect messages. |
Check the value of the "accept_redirects" variables with the following command:
$ sudo sysctl net.ipv4.conf.all.accept_redirects
net.ipv4.conf.all.accept_redirects = 0
If the returned line does not have a value of "0", a line is not returned, or the line is commented out, this is a finding.
Check that the configuration files are present to enable this network parameter.
$ sudo grep -r net.ipv4.conf.all.accept_redirects /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf
/etc/sysctl.d/99-sysctl.conf: net.ipv4.conf.all.accept_redirects = 0
If "net.ipv4.conf.all.accept_redirects" is not set to "0", is missing or commented out, this is a finding.
If conflicting results are returned, this is a finding.